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Nova/Supernova
|-|Nova= |-|Supernova= Summary A nova or classical nova is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star, that slowly fades over several weeks or many months. Novae involve an interaction between two stars that cause the flare-up that is perceived as a new entity that is much brighter than the stars involved. Causes of the dramatic appearance of a nova vary, depending on the circumstances of the two progenitor stars. All observed novae involve closely located binary stars (the progenitors), either a pair of red dwarfs in the process of merging, or a white dwarf and another star. They are all considered to be cataclysmic variable stars. Luminous red novae share the name and are also cataclysmic variables, but are a different type of event caused by a stellar merger. Also with similar names are the much more energetic supernovae (SNe) and kilonovae. A U Geminorum-type variable star, or dwarf nova is a type of cataclysmic variable star consisting of a close binary star system in which one of the components is a white dwarf that accretes matter from its companion. They are similar to classical novae in that the white dwarf is involved in periodic outbursts, but the mechanisms are different. Classical novae result from the fusion and detonation of accreted hydrogen on the primary's surface. Current theory suggests that dwarf novae result from instability in the accretion disk, when gas in the disk reaches a critical temperature that causes a change in viscosity, resulting in a temporary increase in mass flow through the disc, which heats the whole disc and hence increases its luminosity. Dwarf novae are distinct from classical novae in other ways; their luminosity is lower, and they are typically recurrent on a scale from days to decades. A kilonova (also called a macronova or r-process supernova) is a transient astronomical event that occurs in a compact binary system when two neutron stars or a neutron star and a black hole merge into each other. The term kilonova was introduced by Metzger et al. in 2010 to characterize the peak brightness, which they showed reaches 1000 times that of a classical nova. Kilonovae are thought to emit short gamma-ray bursts and strong electromagnetic radiation due to the radioactive decay of heavy r-process nuclei that are produced and ejected fairly isotropically during the merger process. A luminous red nova is a stellar explosion thought to be caused by the merging of two stars. They are characterized by a distinct red color, and a light curve that lingers with resurgent brightness in the infrared. The luminosity of the explosion occurring in luminous red novae is between that of a supernova (which is brighter) and a nova (dimmer). The visible light lasts for weeks or months, and is distinctively red in color, becoming dimmer and redder over time. A supernova is an event that occurs upon the death of certain types of stars. Supernovae are more energetic than novae. Theoretical studies indicate that most supernovae are triggered by one of two basic mechanisms: the sudden re-ignition of nuclear fusion in a degenerate star or the sudden gravitational collapse of a massive star's core. In the first instance, a degenerate white dwarf may accumulate sufficient material from a binary companion, either through accretion or via a merger, to raise its core temperature enough to trigger runaway nuclear fusion, completely disrupting the star. In the second case, the core of a massive star may undergo sudden gravitational collapse, releasing gravitational potential energy as a supernova. The intense radiation of most observed gamma-ray bursts is thought to be released during a supernova or superluminous supernova as a high-mass star implodes to form a neutron star or a black hole. A superluminous supernova, also known as a hypernova, is a type of stellar explosion with a luminosity 10 or more times higher than that of standard supernovae. There are multiple models for what conditions may produce an SLSN, including core collapse in particularly massive stars, millisecond magnetars, interaction with circumstellar material (CSM model), or pair-instability supernovae. Hypernovae produce long gamma ray bursts (GRBs), which range from 2 seconds to over a minute in duration. A quark-nova is the hypothetical violent explosion resulting from the conversion of a neutron star to a quark star. Analogous to a supernova heralding the birth of a neutron star, a quark nova signals the creation of a quark star. When a neutron star spins down, it may convert to a quark star through a process known as quark deconfinement. The resultant star would have quark matter in its interior. The process would release immense amounts of energy, perhaps explaining the most energetic explosions in the universe. Powers and Stats Tier: 5-A for nova (far lower for dwarf nova), High 5-A for kilonova, High 4-C for luminous red nova, High 4-C to 4-B for supernova/hypernova, 4-B for quark-nova Name: Nova, Dwarf Nova, Kilonova, Luminous Red Nova, Supernova, Hypernova, Quark-Nova Origin: Real Life Classification: Nova, Kilonova, Luminous Red Nova, Supernova/'Hypernova', Quark-Nova Powers and Abilities: Massive explosions occurring at the surface or deep within stars that results from their (partial) destruction, releasing relativistic high-energy particles, gamma-ray bursts, high energy radiation, and strong gravitational waves Attack Potency: Large Planet level for nova (1037 Joules), far lower for dwarf nova (only releases a tiny fraction of the energy of a classic nova), Dwarf Star level for kilonova (1039 to 1041 Joules), Large Star level for luminous red nova (5×1043 Joules), Large Star level to Solar System level+ for supernova/hypernova (1044 to 1046 Joules), Solar System level+ for quark-nova (1047 Joules) Speed: [[wikipedia:GRB 080916C|Up to Relativistic+ for expelled stellar plasma]], Relativistic+ to Speed of Light for gamma radiation (very-high-energy gamma rays may be slowed down as they propagate through the quantum turbulence of space-time), Speed of Light for gravitational waves Category:Real World Category:Natural Phenomena Category:Events Category:Tier 5 Category:Tier 4